Uhh... it's Dean Stockwell, not Spockwell. He doesn't have pointed ears.
And in 1969, William Windom would've been 46, closer to Al's age than Sam's. And he was definitely more the grizzled sidekick type than the leading man type.
And they did make QL 20 years earlier, and called it The Time Tunnel
. Honestly, they have exactly the same setup. The main difference is that TTT was about travelling between different important historical events that could be represented by stock footage from old movies, while QL was an anthology disguised as an ongoing series, dropping its lead character into different dramatic situations at various points in recent history but shying away from big events.
If QL had been made in 1969, it probably would've been less like QL and more like TTT. Part of the reason for QL's format was that it was a reaction to decades of time-travel stories that focused on big historical events. To some degree, it was specifically trying to be different from TTT and other shows and films that used that cliche. 20 years earlier, it wouldn't have been seen as such a cliche, and television and popular culture in general wouldn't have been at a point where they sought to deconstruct previous pop-culture cliches.
On the other hand, QL's pseudo-anthology drama approach is very '60s in its way, reminiscent of shows like The Fugitive
. So maybe a show using its format, taking a more grounded, dramatic approach and keeping the sci-fi elements (and associated expense) to a minimum, could've come along in the '60s, if it had occurred to someone to try it. Maybe Rod Serling could've pulled it off. It would've been seen as a very innovative approach to genre TV, bringing a new maturity to it, but that very maturity would've made it much harder to sell the idea to executives with preconceptions about what sci-fi was like. On the other hand, the pseudo-anthology format could've helped sell it, since it's a format the execs were already familiar with.